1. Field of the Invention
The present invention relates generally to methods and systems for production of hydrocarbons and/or other products from various subsurface formations such as hydrocarbon containing formations.
2. Description of Related Art
Hydrocarbons obtained from subterranean formations are often used as energy resources, as feedstocks, and as consumer products. Concerns over depletion of available hydrocarbon resources and concerns over declining overall quality of produced hydrocarbons have led to development of processes for more efficient recovery, processing and/or use of available hydrocarbon resources. In situ processes may be used to remove hydrocarbon materials from subterranean formations that were previously inaccessible and/or too expensive to extract using available methods. Chemical and/or physical properties of hydrocarbon material in a subterranean formation may need to be changed to allow hydrocarbon material to be more easily removed from the subterranean formation and/or increase the value of the hydrocarbon material. The chemical and physical changes may include in situ reactions that produce removable fluids, composition changes, solubility changes, density changes, phase changes, and/or viscosity changes of the hydrocarbon material in the formation.
Large deposits of heavy hydrocarbons (heavy oil and/or tar) contained in relatively permeable formations (for example, in tar sands) are found in North America, South America, Africa, and Asia. Tar can be surface-mined and upgraded to lighter hydrocarbons such as crude oil, naphtha, kerosene, and/or gas oil. Surface milling processes may further separate the bitumen from sand. The separated bitumen may be converted to light hydrocarbons using conventional refinery methods. Mining and upgrading tar sand is usually substantially more expensive than producing lighter hydrocarbons from conventional oil reservoirs.
In situ production of hydrocarbons from tar sand may be accomplished by heating and/or injecting fluids into the formation. U.S. Pat. No. 4,084,637 to Todd; U.S. Pat. No. 4,926,941 to Glandt et al.; U.S. Pat. No. 5,046,559 to Glandt, and U.S. Pat. No. 5,060,726 to Glandt, all of which are incorporated herein by reference, describe methods of producing viscous materials from subterranean formations that includes passing electrical current through the subterranean formation. Steam may be injected from the injector well into the formation to produce hydrocarbons.
Oil shale formations may be heated and/or retorted in situ to increase permeability in the formation and/or to convert the kerogen to hydrocarbons having an API gravity greater than 10°. In conventional processing of oil shale formations, portions of the oil shale formation containing kerogen are generally heated to temperatures above 370° C. to form low molecular weight hydrocarbons, carbon oxides, and/or molecular hydrogen. Some processes to produce bitumen from oil shale formations include heating the oil shale to a temperature above the natural temperature of the oil shale until some of the organic components of the oil shale are converted to bitumen and/or fluidizable material.
U.S. Pat. No. 3,515,213 to Prats, which is incorporated herein by reference, describes circulation of a fluid heated at a moderate temperature from one point within the formation to another for a relatively long period of time until a significant proportion of the organic components contained in the oil shale formation are converted to oil shale derived fluidizable materials.
U.S. Pat. No. 7,562,707 to Miller and U.S. Pat. No. 7,635,024 to Karanikas, all of which are incorporated herein by reference, describe methods and heaters for treating a hydrocarbon containing formation that includes providing heat from a plurality of heaters to mobilize hydrocarbons in the hydrocarbon formation.
U.S. Pat. No. 7,798,220 to Vinegar et al.; U.S. Pat. No. 7,717,171 to Stegemeier; U.S. Pat. No. 7,841,401 to Vinegar et al.; U.S. Pat. No. 7,739,947 to Stegemeier et al.; U.S. Pat. No. 7,681,647 to Mundunuri et al.; U.S. Pat. No. 7,677,314 to Hsu; U.S. Pat. No. 7,677,310 to Vinegar et al.; and U.S. Pat. No. 7,673,681 to Vinegar et al., all of which are incorporated herein by reference, describe methods for treating hydrocarbon formations that include heating hydrocarbons layers with heaters in combination with a drive and/or oxidizing fluid.
U.S. Pat. No. 7,073,578 to Vinegar et al., which is incorporated herein by reference describes a conduit placed inside an opening between a liner and a heater. The liner includes openings that allows fluid to flow through the liner. Steam may be provided to the conduit to inhibit coking along a length of the liner such that openings in the liner are not clogged and fluid flow through the openings is maintained.
U.S. Patent Publication No. 2009/0260812 to Reynolds et al., which is incorporated herein by reference, describes providing water through one or more wellbores to at least a portion of a hydrocarbon containing formation and combusting at least a portion of a fuel stream comprising hydrogen sulfide in the presence of an oxygen source in one or more heaters positioned in one of the wellbores to produce a combustion by-products stream. Heat from the combustion is transferred to a portion of the hydrocarbon containing formation. The combustion by-products stream includes one or more sulfur oxides. Heat of solution is released by contacting at least a portion of the combustion by-products stream with a portion of the water and/or a portion of water in the hydrocarbon containing formation.
As discussed above, there has been a significant amount of effort to produce hydrocarbons and/or bitumen from hydrocarbon containing formations. At present, however, there are still many hydrocarbon containing formations that cannot be economically produced. Thus, there is a need for improved methods for heating of a hydrocarbon containing formation that contains, for example, bitumen, and production of bitumen and/or liquid hydrocarbons having desired characteristics from the hydrocarbon containing formation are needed.